A comprehensive study of the stress release and structural changes caused by postdeposition thermal annealing of tetrahedral amorphous carbon ͑ta-C͒ on Si has been carried out. Complete stress relief occurs at 600-700°C and is accompanied by minimal structural modifications, as indicated by electron energy loss spectroscopy, Raman spectroscopy, and optical gap measurements. Further annealing in vacuum converts sp 3 sites to sp 2 with a drastic change occurring after 1100°C. The field emitting behavior is substantially retained up to the complete stress relief, confirming that ta-C is a robust emitting material.

Heavy crude oil and bitumen resources are more than double the conventional light oil reserves worldwide. Heavy crude oil and bitumen production is on average twice as capital and energy intensive as the production of conventional oil. This is because of their extremely low mobility due to high viscosity at reservoir conditions alongside the presence of undesirable components such as asphaltenes, heavy metals and sulphur making it more challenging to produce, transport as well as refine. It is well know that pipelines are the most convenient means of transporting crude oil from the producing field to the refinery. However, moving heavy crude oil and bitumen is extremely challenging because of their inability to flow freely. As such, without prior reduction in the heavy crude oil and bitumen viscosity, transportation via pipeline is difficult. This is because of the huge energy (i.e. high pumping power) required to overcome the highpressure drop in the pipeline due to their high viscosity at reservoir conditions. To reduce this high-pressure drop and cost of transportation, several technologies have been proposed to improve the flow properties of the heavy crude oil and bitumen through pipelines. In this study, different technologies are reviewed and the advantages and disadvantages of each technology are highlighted with the view that the review will provide direction for improvement and development of novel technologies for bitumen and heavy oil transportation via pipelines.

Field emission has been measured from a series of tetrahedrally bonded amorphous carbon (ta-C) films produced by the filtered cathodic vacuum arc. The threshold field and current densities achievable have been studied as a function of their sp3 content and of nitrogen incorporation. Typical undoped ta-C films are found to have a threshold field of 10–20 V/μm, decreasing with increasing sp3 content, and optimally nitrogen doped films exhibit threshold fields as low as 3–5 V/μm.

Toe-to-heel air injection (THAI) and its catalytic version CAPRI are relatively new technologies for the recovery and upgrade of heavy oil and bitumen. The technologies combine horizontal production well, in situ combustion, and catalytic cracking to convert heavy feedstock into light oil down-hole. The deposition of asphaltenes, coke, and metals can drastically deactivate the catalyst in the CAPRI process. A fixed bed microreactor was used to experimentally simulate the conditions in the catalyst zone of the oil well of CAPRI. In this study, oil upgrading and catalyst deactivation in the CAPRI process were investigated in the temperature range of 350−425°C, pressure of 20 barg and residence time of 9.2 min. Additionally, a guard bed consisting of activated carbon particles prior to the active catalyst in a microreactor and/or the addition of hydrogen to the gas feed were used to minimize coke formation and catalyst deactivation through respectively removing and hydrocracking the coke precursors. It was found that depending on the upgrading temperature, the viscosity of the produced oil reduced significantly by 42−82% and (American Petroleum Institute) API gravity increased by ∼2 to 7°API relative to the feedstock of 0.49 Pa·s and 13°API, respectively. Conversely, the use of hydrogen further increased the API gravity by 2°API and the viscosity by 5.3%. Notably, the coke content of the catalyst reduced from 57.3 wt % in nitrogen to 34.8 wt % in hydrogen atmosphere. The use of a guard bed increased the API gravity of the produced oil by a further 2°and reduced the viscosity by an average of 8.5% further than achieved with the active HDS catalyst CoMo/alumina.

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